Access gateways are widely used to connect devices in a home to the Internet or any other wide area network (WAN). Access gateways use in particular digital subscriber line (DSL) technology that enables a high data rate transmission over copper lines or optical lines. Residential gateways, as well as other devices such as routers, switches, telephones and set-top boxes, are understood in this context as customer premises equipment (CPE) devices.
Access gateways including wireless technology have a key role in today's home and professional environments. A mechanism for connecting wireless devices to a local area network (LAN) is called Wi-Fi, which is a brand name of the Wi-Fi Alliance for devices using the IEEE 802.11 family of standards for wireless data transmission. The IEEE 802.11 standards define two types of wireless nodes, a general wireless device that can connect to other devices called a station (denoted as STA) and a special type of a STA that is in control of the network, namely an access point (denoted AP). A Wi-Fi network, often called a WLAN (wireless local area network), consists of an AP with one or several STA connected to the AP.
Due to its flexible and “invisible” nature, a lot of LAN applications are utilizing Wi-Fi rather than the classical wired Ethernet approach. This widespread usage of wireless LAN has exposed however a serious downside of using a shared medium technology: interference. Interference, both Wi-Fi and non-Wi-Fi related, leads to a degraded user experience due to the nature of IEEE 802.11. In its most common form, IEEE 802.11 networks apply a medium access method in which collisions are avoided by sensing that the medium is used (denoted as CSMA-CA). The medium access method is also commonly known as “listen before talk”, describing the essence of the method and is referred to as “Clear Channel Assessment” (CCA). Clear channel assessment determines whether a wireless communication channel is “occupied”, e.g., “busy” with another wireless communication and/or has an amount of interference that makes the wireless communication channel unsuitable for communication. In this way, it is determined whether the wireless communication channel is available or not available for communication, e.g. occupied or not occupied.
Another impact of interference can be packet loss at the receiver side, leading to a reduction of the physical layer rate. The physical layer rate, also referred to in the following as “TrainedPhyRate” or modulation rate, relates to the transfer rate on the physical layer of the wireless connection. The IEEE 802.11 MAC protocols use rate adaptation mechanisms for evaluating the properties of the wireless channel and select an appropriate physical layer rate. In this case, the interference is not detected by the CCA of the transmitter, but is decreasing the SINR (Signal to Noise and Interference Ratio) of the Wi-Fi packets as seen by the receiver. Typically, Wi-Fi nodes will react to packet loss by lowering the physical layer rate used towards a more robust—but slower—physical layer rate in an attempt to increase the chance of successfully transmitting packets.
Therefore, in certain circumstances, the Wi-Fi connection can suffer from poor performance and even connection loss. Some of these circumstances are obvious and easy to explain to an end user. For example, if the distance between the station and the AP is too large, then signal levels are low and performance will degrade. Other circumstances are “invisible” and not understood by the end user, e.g. a hidden node. A hidden node is invisible to some of the nodes of a network, leading to a practical failure of the CSMA-CA method, which can cause packet collision/corruption over air. In many cases, the end user is not able to diagnose the problem source and correct the issue.
For in-home Wi-Fi networks, connectivity and performance issues are correspondingly one of the main Internet service provider support costs and causes for help-desk calls. Today's focus for operators is mainly on Wi-Fi network installation, associating a station with an AP. Internet service providers are therefore searching for ways to get a better understanding of the end user's wireless environment including link quality and performance.
The ideal way to analyze Wi-Fi issues, e.g. connection setup, interference, throughput, etc., is by looking into the master node of the wireless LAN, namely the AP. The AP, as defined in IEEE 802.11, controls the network, hence all data and network control is visible by the AP. The AP today can deliver statistics regarding packet transmission and signal levels. But the real issue why a link is dropped or why throughput is low, remains hidden to the internals of the AP. Today, at best an AP can deliver statistics but no view on what is actually happening in the wireless network.
Wi-Fi performance can be degraded because of the following categories. For each category, a different action has to be taken to improve things:                Power Save settings of the Station                    Change power save setting of the station                        Sharing the medium (properly) with other Wi-Fi devices                    Use another channel that is less occupied (or prioritize Wi-Fi traffic properly using e.g. Wi-Fi Multimedia priorities (WMM, IEEE 802.11e)                        Interference at Transmitter side                    Change to channel without interference (or remove interference source)                        Interference at Receiver side                    Change to channel without interference (or remove interference source)                        Physics: high path loss, impossibility to set up multiple spatial streams                    move AP or station                        
The problem to solve is to have an application that can correctly analyze Wi-Fi performance issues and indicate the correct category causing the issue, so that the end user can be guided to a suitable corrective action.